PURPOSE: To describe the clinical phenotype in a family with primary open angle glaucoma harboring a p.Gln368X mutation in MYOC. MATERIALS AND METHODS: We identified a proband with primary open angle glaucoma and the p.Gln368X MYOC mutation. She and her six siblings were examined clinically, including Heidelberg Retina Tomography II, and venous blood samples were screened for other variants in MYOC, WDR36, OPTN, and CYP1B1. RESULTS: Four individuals showed the p.Gln368X MYOC mutation, no other genetic variations were assessed. Two of these four siblings had glaucomatous optic disc changes with corresponding visual field losses and abnormal Heidelberg Retina Tomography results by the Moorfields regression analysis, one had abnormal results by the Moorfields regression analysis but no visual field loss, and one showed no glaucomatous signs or symptoms at all. These findings did not correlate with the age of the affected individuals. CONCLUSION: In the primary open angle glaucoma family described here, we documented a wide range in clinical symptoms, demonstrating a highly variable penetrance of the MYOC p.Gln368X mutation.